Doppler laser radar systems operating in heterodyne detection mode are used for remote measurements of atmospheric winds. In order to be used within a laser radar system, the laser must provide a powerful pulse of optical energy at a very narrow bandwidth (single longitudinal and transverse mode). Such a narrow line is achieved utilizing two laser components in an injection-seeding master oscillator/power-amplifier system. Generally, in such a system the master oscillator or seed laser is a low power highly stable, continuous wave laser while the power amplifier or slave laser is a high power pulsed laser operating at a single frequency established by the seed laser.
Utilizing a ring resonator configuration for the slave oscillator provides important advantages such as: a traveling wave (eliminating "spatial hole burning"); a long resonator within a compact frame; and direct and simple laser seeding. Active control of the ring resonator length is essential for single frequency operation of the laser. U.S. Pat. No. 5,099,486 presents a ring laser resonator invention with a type of resonant path length control which, although independent of the invention presented herein, may be utilized in combination with the present invention to improve path length control.
It is an object of this invention to present a method and apparatus for providing a high power, high repetition rate, single frequency laser source.
It is another object of this invention to present a new method and apparatus for providing injection-seeding feedback control for ring slave lasers for use in such laser sources.
It is another object of the present invention to provide an active injection seeding stabilizer for ring slave lasers for use in such laser sources.
It is a further objective of this invention to provide an actively stabilized injection seeded ring laser system.